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J201 vs MPF102 in minibooster

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5/18/2000 9:01 PM

J201 vs MPF102 in minibooster

the minibooster is a clean boost circuit i built from this schematic.

i used MPF102's because they were readily available. the site says that J201's are better tho. now that i heard it, i like it slightly better than what i'm using now, but i wonder if it's worth finding some J201's for it. any idea what diff i'll hear using J201 vs the MPF102? i realize it's not likely easy to tell me this w/o actual experience with this circuit, but some of you guys are so experienced that i figured someone may be very familiar with these common transistors and how they'd difference in a circuit like this.

thanks,-dale

5/18/2000 9:25 PM

Dale, I'm not one of the experts, but I've made the minibooster with MPF102s and J201s. The latter has more gain, which is a cruicial difference in this circuit. This gives you more output and better drive capability when trying to overload succesive stages of miniboosters. There is also a subtle difference in sound between them. I don't really know how or why, but the J201s sound almost warmer to me while the MPF102s sound a tad clearer-- I'm talking very small differences here, which could be my imagination. But j201s aren't expensive and can be had readily from radioshack.com.

jake

5/18/2000 10:31 PM
John Greene	The biggest difference you'll notice is in battery life. The MPF102 version will have a significantly higher bias current that the J201 version. I think it's the bottom JFET that sets the DC current through the two so putting a MPF102 on top with a J201 on the bottom may be an interesting combination. --johng

5/18/2000 11:36 PM
aron	I've tried this and other combinations. I think one of my schematics had the MPF102 on top and NTE458 on bottom. Aron

5/19/2000 6:39 AM

quote:
"I think it's the bottom JFET that sets the DC current through the two so putting a MPF102 on top with a J201 on the bottom may be an interesting combination.
"

John, I believe it's the other way around. Anyway, trying different combinations is a good thing, just watch for different pin-outs on those jfets.

-Eric

5/19/2000 2:03 PM
anonymous	DC current through the circuit is dependent on both jfets.

5/19/2000 7:46 PM
STEVE	I'M CONFUSED NOW BUT REGARDLESS ANYONE HAVE THE PARTS NUMBER OF THE J201'S FROM RADIOSHACK PO LEEZEEEEEE I WANTS TO ORDER NOW AS SOMEONE DEAD WOULD HAVE SAID THANK YOU THANK YOU VERY MUCH

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